Helmets comprising adjustability features are known. In this regard, it Is known to provide an adjustable helmet having two shell portions that are held tog ether by screws. The loosening and tightening of the screws allow for the adjustment of the helmet. Such adjustment means however require the use of tools such as screwdrivers or the like and are therefore impractical. Furthermore, they do not allow one to readily adjust a helmet while wearing it. The initial adjustment thus has to be approximate and proper fit is achieved on a trial and error basis.
Efforts have thus been made to improve the conventional adjustable helmet by implementing therein an adjustment mechanism that does not require any tools. An example of such mechanism is found in U.S. Pat. No. 4,539,715 issued on Sep. 10, 1985 and assigned to the present applicant. The adjustable helmet described in that patent, which is commercially available under the trademark COOPER XL7, comprises two shell portions with mating surfaces having teeth that overlap and engage with one another to retain the shell portions in a given overlapping position. The mating surfaces are held in engagement by a locking mechanism that comprises a cam member and a bracket having extending tabs comprising sockets into which extend pins fixed to the cam member, the tabs defining the axis of swivel of the cam member. When the bracket and cam member are in a locking position, they cooperate to retain the mating surfaces in an overlapping relationship. When they are in an adjustment position, the mating surfaces may move relative one another since the tabs are slidingly moveable within longitudinal slots to allow for the adjustment of the helmet.
The adjustment mechanism provided for in U.S. Pat. No. 4,539,715 possesses however various limitations which negatively affect its performance. First, the axis of swivel of the cam member is generally perpendicular relative to the side portions of the helmet and is generally parallel to the teeth. Therefore, the orientation of the cam member relative to the teeth is such that the cam member fails to apply a compressive force along a significant number of the teeth. This reduces the compressive force exerted on the teeth and allows the shell portions to disengage and move relative one another during a severe impact, such as when a hockey player hits the board, even when the adjustment mechanism is in a "locked" position. Also, because of the generally rectangular cross-sectional shape of the bracket's extending tabs and of the corresponding longitudinal slots, the locking mechanism of this patent only allows for an adjustment in a direction that is perpendicular to the axis of swivel of the cam member. In other words, the back shell is only moveable in a forward-rearward direction relative to the front shell. This is impractical since it has been discovered that better adjustment may be provided when the back shell moves angularly relative to the front shell.
Another disadvantage is that the generally rectangular cross-sectional shape of the tabs and longitudinal slots does not allow one to easily replace the locking mechanism by conventional mounting screws.